code: def pytest_collection_modifyitems(items):
      n_splits = int(os.environ.get("HAIL_RUN_IMAGE_SPLITS", "1"))
      split_index = int(
          os.environ.get("HAIL_RUN_IMAGE_SPLIT_INDEX", "-1")
      )
      if n_splits <= 1:
          return
      if not (0 <= split_index < n_splits):
          raise RuntimeError(
              f"invalid split_index: index={split_index}, n_splits={n_splits}\n  env={os.environ}"
          )
      skip_this = pytest.mark.skip(reason="skipped in this round")
  
      def digest(s):
          return int.from_bytes(
              hashlib.md5(str(s).encode("utf-8")).digest(), "little"
          )
  
      for item in items:
          if not digest(item.name) % n_splits == split_index:
              item.add_marker(skip_this)
  
file_path: hail/hail/python/test/hail/conftest.py
imports: from typing import Dict
  import asyncio
  import hashlib
  import os
  import logging
  import pytest
  from pytest import StashKey, CollectReport
  from hail import current_backend, init, reset_global_randomness
  from hail.backend.service_backend import ServiceBackend
  from hailtop.hail_event_loop import hail_event_loop
  from hailtop.utils import secret_alnum_string
  from .helpers import hl_init_for_test, hl_stop_for_test
label_desc: Use image node_id 2 for calling a global function with example usage: pytest_collection_modifyitems(items) and returns: int